[Ifeffit] Phase transformation and space group

[益豪]

To Dear authors:

We have complex perovskites, the series of La(2-x)/3 Nax Mg0.5 W0.5 O3 where x=0,0.1,0.2,0.3,0.4,0.5. I would like to fit the EXAFS data, and according as ICSD to build the atom list by using TkAtoms. However these samples might have phase transformation with the increase in x-value. 
First, I use the same structure which the x=0 atom coordinates from ICSD to fit the data of x=0-0.2, and use the x=0.5 atom coordinates to fit the data of x=0.3-0.5. But the trend of the distance between the central atom(W) and the six neighboring oxygen atoms with Na concentration is very strange! The distance of O-W with x=0-0.2 is increasing, x=0.2-0.3 is decreasing, and x=0.3-0.5 is increasing.
I conjecture that the result is so strange because we use the different space group.
I would like to ask how to choose the atom coordinates x=0 and x=0.5 from ICSD to build the theoretical model of x=0.1-0.4.
Thanks for your time and help!
 
Yi-Hao, Chang


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